1. Field of the Invention
This invention relates to a method and apparatus for attaching a throttle plate to a throttle shall for an automotive engine.
2. Related Art
An engine throttle valve is installed in a throttle body receiving inlet that receives air flow from an intake manifold. The throttle valves typically have a throttle plate disc that is attached to a throttle shaft that is mounted to extend across the bore of the inlet. The throttle shaft is used to rotate the throttle plate to variably control air flow within the bore.
Usually the throttle plate and the throttle shaft are constructed of metal and are attached to each other with screws or other fasteners. The fasteners can loosen over time and be drawn into the engine causing damage. The use of fasteners also increases assembly time and cost.
Another attachment method uses ultrasonic heat staking to attach a plastic throttle plate to a plastic throttle shaft. The shaft has bosses that are received in openings formed on the plate. Ultrasonic staking causes localized melting that secures the bosses to the plate. This attachment method can fail due to the small area of contact between the boss and the plate.
It is the object of the present invention to provide an improved throttle shaft and plate assembly that eliminates the use of fasteners and provides a more secure attachment between the throttle plate and shaft.
In a disclosed embodiment of this invention, a throttle assembly includes a throttle shaft and a throttle plate. The throttle shaft defines a longitudinal axis and is formed with a flat surface extending partially along the length of the shaft. A first set of ribs is supported on the flat surface. The ribs are positioned in a transverse relationship lo the longitudinal axis. The throttle plate has a body with a locating portion that properly positions the plate with respect to the shaft. A second set of ribs is supported on one side of the body. The second set of ribs is positioned transversely to and in abutting engagement with the first set of ribs when the locating portion engages the shaft. The first and second sets of ribs are welded together to secure the plate to the shaft.
In a preferred embodiment, the throttle plate and shaft are formed from a non-metallic material. The first set of ribs is integrally formed with the shaft as one piece and the second set of ribs is integrally formed with the plate as one piece. Preferably the second set of ribs is perpendicular to the first set of ribs and the first set of ribs is perpendicular to the longitudinal axis.
In one embodiment, the shaft includes a boss formed in a first predetermined shape that projects from the shaft. The locating portion is preferably a hole formed within the plate body and has a second predetermined shape that corresponds to the first predetermined shape. The boss is inserted into the hole to locate the plate with respect to said shaft.
A method for assembling the throttle plate to the throttle shaft includes the following steps. A first plurality of ribs is formed on the throttle shaft and a second plurality of ribs is formed on the throttle plate. The throttle plate is located with respect to the throttle shaft and the second plurality of ribs is abutted against the first plurality of ribs. The throttle plate is attached to the throttle shaft by supplying weld energy along the interface between the first and second plurality of ribs.
The subject apparatus and method of assembly provide a simplified attachment process that eliminates components and reduces assembly time and cost. The inventive apparatus and method of assembly also provides a secure and enduring connecting between the throttle shaft and plate.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.